Abstract
The human brain is remarkably adept at extracting identity information from faces, although understanding this process remains a challenge. Here, a novel neural measure of objective discrimination between two individual face identities at the system level of organization is presented. This measure utilizes fast periodic visual stimulation (FPVS) in electroencephalography (EEG) combined with an adaptation paradigm (as in Ales & Norcia, 2009). Adaptation to a facial identity is induced through repetition of one identity displayed over a 10-second baseline, flickering at a base rate of 6 images per second (6 Hz). Subsequently, this identity is alternated with its anti-face, from a multidimensional face space (e.g., Leopold et al., 2001), over 20 seconds at the same rate. During the alternation of the two identities, a response exactly at half the base presentation rate (i.e., at 3 Hz), localized over the right occipito-temporal cortex, indicates that adaptation has produced an asymmetry in the perception of the two facial identities. Importantly, this 3 Hz response is not observed in a control condition without the single-identity baseline, while the response at the 6 Hz base presentation rate does not differ between conditions. These results indicate that neural adaptation to one identity can produce a measurable electrophysiological discrimination response between that identity and another, which could be further investigated with different categories or specific face pairs in future studies to increase understanding of individual face representation.
Meeting abstract presented at VSS 2015